1. Technical Field
The present invention relates to an electro-optical device and an electronic apparatus, and more particularly to a double-sided displaying type electro-optical device which is less affected by interference fringes and an electronic apparatus having the electro-optical device.
2. Related Art
As for electro-optical devices, liquid crystal display (LCD) devices have been widely used. The liquid crystal display device includes a plurality of pixel regions provided between opposing electrodes and modulates light passing through a liquid crystal material provided at the pixel regions by selectively applying a voltage to the pixel regions, thereby displaying an image of pictures or characters as a whole.
Recently, double-sided displaying type LCD devices have been developed in order to realize multifunctional display devices. However, known double-sided displaying type LCD devices have a problem in that it has relatively lower brightness in comparison with single-sided displaying type liquid crystal display devices, that is, it is impossible to achieve sufficient brightness because light from a single light source and a single light guiding plate enters two liquid crystal panels.
In order to solve the above-mentioned problem, JP-A-2004-46050 discloses another double-sided displaying type LCD device as shown in FIG. 14. In this LCD device, LCD panels 307 and 308 are arranged on both sides of a single light guiding plate 302, respectively, which has an end with a light source 301 thereon, reflective polarizing plates 305 and 306 are interposed between the light guiding plate 302 and the LCD panel 307 and between the light guiding plate 302 and the LCD panel 308, respectively, and transmission axes of the reflective polarizing plates 305 and 306 are adjusted in the following manner.
In greater detail, the transmission axes of the reflective polarizing plates 305 and 306 are aligned with transmission axes of liquid crystal panel polarizing plates 309 and 310, respectively, facing the reflective polarizing plates 305 and 306. That is, the transmission axes of the reflective polarizing plate 305 and the liquid crystal panel polarizing plate 309 disposed on the same side with respect to the light guiding plate 302 are aligned with each other, and the transmission axes of the reflective plate 306 and the liquid crystal panel polarizing plate 310 disposed on the same side with respect to the light guiding plate 302 are aligned with each other. On the other hand, the transmission axes of the reflective polarizing plate 305 and the liquid crystal panel polarizing plate 309 disposed on the same side with respect to the light guiding plate 302 orthogonally intersect the transmission axes of the reflective polarizing plate 306 and the liquid crystal panel polarizing plate 310 disposed on the opposite side across the light guiding plate 302.
However, the double-sided displaying type LCD device disclosed in the above-mentioned patent document still encounters many problems. For example, light from a light source cannot be effectively used and light is not uniformly guided over the entire area of the light guiding plate. As for the double-sided displaying type LCD device, there is a further known technique in which a light guiding plate having an inclined portion (also called a wedge portion) which becomes thicker as it becomes nearer a light source is used in the LCD device. This LCD device also has a problem in that light is apt to leak from the inclined portion and thus interference fringes are easily formed.